Rubber-modified acrylic copolymer thermoset

ABSTRACT

Novel thermoset materials of improved impact, strength and fatigue properties are prepared from an alpha-beta olefinically unsaturated copolymer of vinyl monomers and a crosslinking amount of particulate graded-rubber having alpha-beta olefinicunsaturation surface functionality. The graded-rubber particles have a rubbery core and a glass-like polymeric shell.

United States Paten Dickie et al. 1

[451 Oct. 17,1972

1541 RUBBER-MODIFIED ACRYLIC COPOLYMER THERMOSET [72] Inventors: Ray A.Dickie, Pleasant; Santokh S. Labana, Dearborn Heights, both of Mich.

[73] Assignee: Ford Motor Company, Dearborn,

Mich.

[22] Filed: Dec.2l, 1970 [21] Appl. No.: 100,468

[52] US. Cl. ..260/836, 260/830 TW, 260/835 [51] Int. Cl. ..C08g 45/04[58] Field of Search ..260/831, 834, 836, 835, 859,

[56] 9 References Cited UNITED STATES PATENTS 3,437,514 4/1969 Burlant..1 17/9331 3,450,796 6/1969 Griffin ..260/8 85 3,502,745 3/1970 Minton..260/881 3,528,844 9/1970 Burlant ..260/881 Primary Examiner-PaulLieberman Attorney-John R. Faulkner and Olin B. Johnson [57] ABSTRACThave a rubbery coreand a glass-like polymeric shell.

13 Claims, No Drawings RUBBER-MODIFIED ACRYLIC COPOLYMER THERMOSET THEINVENTION This invention is concerned with novel thermoset materials formolding and with the molded products thereof. The thermoset materials ofthis invention comprise an alpha-beta olefinically unsaturated copolymerof vinyl monomers and graded-rubber particles having alpha-betaolefinic-unsaturation surface functionality. Thermosets of thisinvention are compatible with conventional molding techniques, e.g.,compression, injection, etc., and applicable to the production ofstructural materials as, for instance, automobile structural panels,electrical appliance housings, boat construction, conduits, etc.

l. The Copolymer of Vinyl Monomers The alpha-beta olefinicallyunsaturated copolymer of vinyl monomers used herein advantageously haveaverage molecular weight in the range of about 1,500 to about 25,000preferably about 2,000 to about 15,000. The copolymer advantageously hasbetween about 0.5 and about 5, preferably about 0.7 to about 3.5 unitsof alpha-beta olefinic unsaturation per 1,000 units molecular weight.

The vinyl copolymer used herein commonly consists essentially of carbon,hydrogen and oxygen. Suitable monomers for use in these copolymersinclude methyl methacrylate, hydroxyethyl methacrylate, hydroxypropylmethacrylate, ethyl methacrylate, phenyl methacrylate, benzylmethacrylate, isobornyl methacrylate, cyclohexyl methacrylate, butylmethacrylate, ethyl acrylate, ethyl chloroacrylate, styrene, butylstyrene, chlorostyrene, alpha-methyl styrene, allyl methacrylate, vinylchloride, vinyl acetate, acrylonitrile, methacrylonitrile, methyl vinylether, diethyl fumarate, dimethyl itaconate and glycidyl methacrylate.

In a preferred embodiment, the copolymer has as constituent monomersmethacrylonitrile, an ester of acrylic or methacrylic acid and a C Cmonohydric alcohol, e.g., methyl methacrylate, and an epoxyacrylate,e.g., glycidyl methacrylate. The mixture of monomers is converted to thevinyl copolymer by any of the well known techniques of free radical orionic polymerization methods. Free radical polymerization using azo typeor peroxide type initiator is the preferred method for preparing thecompositions described herein. Alpha-beta olefinic unsaturation isprovided in this embodiment by subsequent reaction of an alphabetaolefinically unsaturated monocarboxylic acid, e.g., acrylic acid,methacrylic acid, etc., with the epoxy groups provided by theepoxyacrylate. This unsaturation can also be provided by substitutingthe alpha-beta olefinically unsaturated monocarboxylic acid for theepoxy acrylate in the polymer-forming reaction and subsequently reactingthe resultant free carboxyl groups with an epoxyacrylate. Other methodsof preparing the copolymer of vinyl monomers are disclosed andillustrated in US. Pat. No. 3,528,844 to W. J. Burlant and C. R. Taylor.11. Preparation of The Graded-Rubber Particles The graded-rubberparticle has a core of crosslinked, elastomeric, acrylic polymer, anouter shell comprising methyl methacrylate and a hydroxy-functionalacrylate and an intermediate layer which is a copolymer of the monomersused to form the core and the monomers used to form the outer shell.

The process for preparing these particulate materials is at least atwo-stage process. In one method of preparation, a major amount ofmono-functional monoacrylate is emulsion copolymerized in the firststage with a crosslinking amount of a dior trifunctional monomercontaining two or more non-conjugated terminal ethylenic groups,preferably a diacrylate, using a water-soluble free radical initiatorand a suitable surfactant to yield a latex of relatively uniformparticle size, e.g., 0.04 to 1 micron average diameter. Before thisreaction reaches substantial completion, i.e., when the reaction isbetween about 50 and about 90, preferably between about 70 and'about 89,percent complete, the second stage monomeric component i.e., a mixtureof about 65 to about 98, preferably about 70 to about 95, mole percentmethyl methacrylate, and about 2 to about 35, preferably about 5 toabout 30 mole percent of an epoxy acrylate, e.g., glycidyl methacrylate,or about 2 to about 35 mole percent of the epoxy acrylate and about 65to about 98 mole percent of a monomer mixture selected from andconsisting essentially of esters of acrylic or methacrylic acid and a CC monohydric alcohol, monovinyl hydrocarbons, diacrylates and divinylhydrocarbons, is added slowly to the reaction mixture. Thepolymerization process is continued to yield a stable latex ofrelatively uniform particle size and composition. A surfactant is usedin forming the emulsion and additional surfactant may be addedsimultaneously with the second stage monomeric component. Alpha-betaolefinic unsaturation is introduced by reacting the epoxy groupsprovided by the epoxyacrylate with an alpha-beta olefinicallyunsaturated monocarboxylic acid, e.g., acrylic acid, methacrylic acid,etc.

The latex is coagulated, washed and dried to yield a finely dividedwhite powder suitable for use in this invention. Generally, theparticles are prepared from monomers that will provide a crosslinkedacrylic, rubber-like core and a glass-like polymeric outer shell at roomtemperature, e.g., 20 30 C. The terms rubber-like and glass-like are, ofcourse, meaningless except when used in reference to a specifictemperature or temperature range. The particles should be formulated sothat the'core retains its rubber-like properties and the outer shellretains its glass-like properties at temperatures encountered byarticles of commerce in the intended field of use. Hence, for practicalpurposes, the monomers should be selected so that the core has a glasstransition temperature that is substantially below that of the outershell. Advantageously, the difference in glass transition temperaturebetween the core and the shell is at least 50 C., preferably above 100C.

The core is formed from a major amount of an alkyl,

monofunctional, monoacrylate and a crosslinking amount of a diortrifunctional monomer containing two or more non-conjugated terminalethylenic groups. The monofunctional, alkyl, monoacrylate is preferablyan ester of a C C monohydric alcohol and acrylic acid, e.g., ethylacrylate, butyl acrylate, hexyl acrylate, 2-ethyl hexyl acrylate and/ormixtures of the same. Certain other alkyl acrylates may be used when thecrosslinked polymer thereof has an appropriate glass transitiontemperature, e.g., dodecyl methacrylate. Butyl acrylate and 2-ethylhexyl acrylate are the most preferred of the monoacrylates for use informing the core. The polymers produced from most methacrylates haveglass transition temperatures which are too high to provide rubber-likeproperties at normally encountered temperatures. Hence, except forspecial use applications, the monoacrylate component of the core will beeither an ester (or esters) or acrylic acid or a mixture of a majoramount of the same and a minor amount of methacrylate.

Suitable crosslinking agents include, but not by way of limitation, 1,3butylene diacrylate, 1,3 butylene dimethacrylate, divinyl benzene, 1,6hexamethylene diacrylate, 1,6. hexamethylene diacrylate, 1,6hexamethylene dimethacrylate, 1,1,1 trimethylolethane triacrylate, 1,1,1trimethylolethane trimethacrylat e, 1,1,1 trimethylolpropanetriacrylate, 1,1,1 trimethylolpropane trimethacrylate, l,4-dimethylolcyclohexane dimethacrylate, allyl acrylate, allylmethacrylate, methallyl acrylate, methallyl methacrylate, diallylmaleate, diallyl fumarate, and diallyl phthalate. In one embodiment, thecrosslinking agent is adiester of acrylic or methacrylic acid and a C Cpreferably C C dihydric alcohol. In another embodiment, thecros'slinking agent is a triester of acrylic or methacrylic acid and a CC preferably C C trihydric alcohol.

In the first reaction stage, there is preferably employed about 80 toabout 98 mole percent of a monofunctional, monoacrylate and about 20 toabout 2 mole percent of the cross-linking agent.

In the second stage reaction, it is preferred to use a mixture of about65 to about 99, preferably about 70 to about 95 percent methylmethacrylate and about 1 to about 35, preferably about 5 to about 30,mole percent of hydroxyalkyl acrylate. These are added before the firstreaction ceases. The amounts of the second stage reactants relative tothe combined first stage reactants may vary widely depending upon thephysical properties desired in the final product, i.e., from about toabout 90 to about 90 to about 10 weight percent.

The methyl methacrylate concentration in the outer shell is advisedly atleast about 30 mole percent with the balance of the monofunctionalcomponent being made up of monofunctional monoacrylates, e.g., esters ofC C monohydric alcohols and either acrylic or methacrylic acid, ormonofunctional vinyl hydrocarbons such as styrene and methyl substitutedstyrenes, e.g., alpha methyl styrene. It will also be advantageous attimes to have a limited amount of crosslinking in the outer shell andhence to include in .said balance a minor amount of a diacrylate, e.g.,l to 30 mole percent of a diester of acrylic or methacrylic acid and a CC dihydric alcohol, or divinyl hydrocarbon, e.g., l to 30 mole percentofdivinyl benzene. The physical properties of the outer shell may also bemodified by replacing up to about 30'mole percent of the methylmethacrylate with acrylonitrile or methacrylonitrile.

The initial monomer charge is usually emulsified by one or-moremicelle-forming compounds composed of a hydrophobic part, such as ahydrocarbon group containing eight or more carbon atoms, and ahydrophilic part, such as alkaline metal or ammonium carboxylate groups,phosphate or sulfate partial ester groups, sulfonate groups, and thelike. Exemplary emulsifying agents include alkali metal sulfonates ofstyrene, naphthalene, decyl benzene and dodecyl benzene; sodium dodecylsulfate; sodium stearate, sodium oleate; sodium alkyl aryl sulfonates;polyoxyethylene sulfates and phosphates; the ethylene oxide condensatewith long chain fatty acids, alcohols, and mercaptans and the alkalimetal salts of rosin acids. These materials and techniques of employmentof emulsion formation and maintenance are well known to the art and'haveno unusual application here. As they are conventional materials employedin a conventional manner, further description is unnecessary.

The polymerization initiator is composed of one or more water-soluble,free-radical-generating species such as hydrogen peroxide or sodium,potassium, or ammonium persulfates, perborates, peracetates,percarbonates and the like. As is well known in the art, theseinitiators maybe associated .with activating systems such as redoxsystems which may incorporate mild reducing agents such as sulfites andthiosulfites and redox reaction-promotors such as transition metal ions.v

A chain transfer agent or a mixture of chain transfer agents may beadded to the reaction medium to limit the molecular weight of thepolymer. Such chain transfer agents are generally mercaptans such asdodecane thiol, pentane thiol, and butane thiol.

Those skilled in the art will be aware that other emulsifying agents,polymerization initiators and chain transfer agents may be used whencompatible with the polymerization system herein employed.

The reaction may be carried out at temperatures from about 40 C. toabout C., or at lower temperatures, as from 0 C. to 80 C. in the case ofactivated systems.

The graded-rubber particles above described and this method ofpreparation are disclosed by Ray A.

Dickie and Seymour Newman in their patent applica tion Ser. No. 100,464filed of even date with this application. III. The Molding CompositionThe molding composition exclusive of reinforcing fibers, particles,etct, commonly consists essentially of a major amount by weight of thealpha-beta olefinically unsaturated copolymer of vinyl monomers andaminor amount by weight of the graded-rubber particles. Vinyl monomersmay be added to the composition to adjust the viscosity to a suitablelevel for the desired molding or processing technique. Nonreactivesolvents may also be used in some embodiments to facilitate distributionof the rubber particles and subsequently removed under reduced pressure.

Any of the commonly available free radical catalysts such as azocompounds, peroxides and peresters may be used to effect cure during themolding process. In some cases, accelerators to enhance curerate such asN,N-dimethyl toluidine, cobalt napthenate and benzoic sulfinimide mayalso be added in less than two percent amounts. In some cases, toprovide stability at room temperature, and fast cure at elevatedtemperatures, accelerators may be used in combination with inhibitorssuch as 2,6 ditertiary butyl phenol, hydroquinone, hydroquinonemonomethyl ether in amounts less than one percent of the total.

The concentration of graded-rubber particles homogeneously dispersed inthe final product can be varied over a wide range in conformance withthe properties desired for such product. Thus, it may be advisable incertain instances for this concentration to range upward from a minimummodifying amount to a major fraction by weight. In the main, however,the concentration and composition of the graded-rubber particles will besuch that the elastomeric cores will comprise a minor proportion byweight of the final product, commonly between about 5 to about 40, morecommonly between about and about 30, weight percent of the finalproduct. The weight relationship of the glass-like outer shell to theelastomeric core can be varied but for most purposes the weight of theouter shell will not substantially exceed that of the core. In

most instances, the average weights of the outer shells will be about 10to about 60, preferably about 20 to about 50, percent of the averageweight of the cores.

This invention will be more fully understood from the following exampleswhich illustrate the thermoset materials hereinbefore described andhereinafter claimed.

EXAMPLE 1 An acrylic prepolymer is prepared by slowly adding a mixtureof 60.0 parts by weight glycidyl methacrylate, 140.0 parts by weightmethyl methacrylate, and 4.0 parts by weight 2,2 azobis (2methyl-propionitrile), to200 parts by weight rapidly stirred toluenemaintained at reflux temperature under a nitrogen atmosphere. Uponcompletion of the addition, 0.2 parts by weight 2,2 azobis (2methylpropionitrile) dissolved in 25 parts by weight toluene is addedover a thirty minute period. The reaction mixture is maintained at 1 10C. for an additional two hours. The reaction mixture is then cooled tobelow 50 C. and there is added 34 parts by weight methacrylic acid, 1.5parts by weight benzyl triethyl ammonium chloride, and 0.2 parts byweight hydroquinone. The mixture is stirred at 85 C. for several hoursuntil titration shown more than 95 percent of the methacrylic acidreacted and infrared analysis shows more than 95 percent of the glycidylgroup consumed. The reaction mixture is cooled, diluted with toluene to30 percent solids, and coagulated in 5 to 7 volumes of hexane. Theresultant white powder hereinafter referred to as Powder B is dried invacuo for 4 hours at 60 C.

About 70 parts by weight of epoxy-functional rubber particles,hereinafter termed Powder A, are dissolved in 150 parts by weightacetone. To this solution is added methacrylic acid in an amountproviding about one carboxyl group per each epoxy group in the outershells of the rubber particles. To the mixture is added a catalyticamount 1.5 parts by weight) benzyl triethyl ammonium chloride. Thedispersion is heated until reaction between the methacrylic acid and theepoxy groups on the graded-rubber particles is substantially complete.The rubber particles are separated from the acetone, dried, anddispersed in 150 parts by weight methyl methacrylate. To this dispersionare added 200 parts by weight of the unsaturated acrylic prepolymerabove termed Powder B and a catalytic amount (0.1 percent by weight)dit-butyl peroxide. The dispersion is compression molded at 100 C. forminutes to yield a hard article insoluble in acetone. By comparison,this mold is much tougher than an identically prepared mold which omitsthe graded elastomeric particles.

Powder A employed above is prepared in the following manner: To 1,000parts by weight water which has been boiled and cooled to roomtemperature under a nitrogen atmosphere are added 2.86 parts by weightsodium dodecyl sulfate dissolved in 35.7 partsby weight water and about1 /6 of a monomer mixture consisting of 348 parts by weight butylacrylate and 32.3 parts by weight 1,3 butylene dimethacrylate. Themixture is stirred to establish dispersion of the monomers. To thestirred mixture are added 3.14 parts by weight potassium persulfatedissolved in 71.4 parts by weight water. The mixture is heated to 45 C.After about 10 minutes, addition of the remainder of the first monomermixture is begun at a rate such that the temperature of the reactionmixture is maintained at 47 to 49 C. The last half of the first monomermixture is added simultaneously with 2.86 parts by weight of sodiumdodecyl sulfate dissolved in 35.7"parts byweight water. Addition of thefirst monomer mixture requires about 45 minutes. The reaction mixture ismaintained at 47 to 49 C. for 35 minutes prior to beginning simultaneousdropwise addition of l) a mixture of 236 parts by weight methylmethacrylate, 143.4 partsby weight glycidyl methacrylate, and 2.57 partsby weight 1 dodecanethiol, and (2) a solution of 5.72 parts by weightsodium dodecyl sulfate in 35.7 parts by weight water. This addition,which requires about 40 minutes, is carried out at such a rate that thetemperature of the reaction mixture is maintained'at 47 to 49 C.Following this addition, the mixture is maintained at 47 to 49 C. for anadditional 2 hours. The resulting latex, which may be termed Latex A, iscooled to room temperature and neutralized with aqueous ammonia. Theoverall conversion of monomers is about 98 percent. The average size ofthese particles is in the range of 0.1 to 0.2 micron. Latex A iscoagulated by adding one volume of latex to approximately 4 volumes ofmethyl alcohol to which has been added 0.001 volume concentratedhydrochloric acid. The coagulum is isolated by filtration, washed withseveral volumes of methyl alcohol, and with water, and is dried in vacuoto yield Powder A.

EXAMPLE 2 The procedures of Example 1 are repeated with the differencethat Powder C is replaced by a prepolymer prepared in the following way:A mixture of parts by weight glycidyl methacrylate, parts by weightmethyl methacrylate, 40 parts by weight methacrylonitrile, and 4 partsby weight 2,2 azobis (2 methylpropionitrile) is added slowly to arefluxing mixture of parts by weight toluene and 150 parts by weightdioxane under a nitrogen atmosphere. The prepolymer obtained is reactedwith 45 parts by weight methacrylic acid using 1.5 parts by weightbenzyl triethyl ammonium chloride'as catalyst in the presence of 0.2parts by weight hydroquinone. Upon completion of this reaction, themixture is diluted with acetone to 30 percent by weight solids and iscoagulated in 5 to 7 volumes of hexane. The resultant white powderhereinafter referred to as Powder C is dried in vacuo at 7 60 C. for 4hours.

Upon substitution of Powder C for Powder B in Example l, a hard moldedarticle is obtained which is insoluble in acetone or toluene. Bycomparison, the molded piece is much tougher than an identicallyprepared molded piece which omits the graded-rubber particles.

EXAMPLE 3 The procedures of Examples 1 to 2 are repeated with thedifference that an equimolar amount of acrylic acid is substituted formethacrylic acid in the reaction with the epoxy groups'on the surfacesof the graded-rubber particles.

EXAMPLE 4 Another thermoset is prepared with incorporation of thegraded-rubber particles in the following manner: Sixty parts by weightglycidyl methacrylate, 140 parts by weight methyl methacrylate, 4 partsby weight 2,2

azobis (2 methylpropionitrile), and six parts by weight 1dodecanethiolare mixed and added to 600 parts by weight water (freshlyboiled to remove dissolved oxygen and cooled to room temperature under anitrogen atmosphere) which contains 1.8 parts by weight polyvinylalcohol) and 18 parts by weight sodium chloride.

The mixture is stirred vigorously and gently heated to 50 C. When anexothermic reaction is observed, external heating is discontinued. Thereaction mixture is maintained at 60 C. for 3 hours. The polymer thusobtained is filtered, washed with methyl alcohol, and dried in vacuo at60 C. for 6 hours.

One hundred-ninety parts by weight of the powder obtained is mixed with150 parts by weight methyl methacrylate, 140 parts by weight Powder Aepoxyfunctional rubber particles), sufficient methacrylic acid toprovide about one acid functionality per each epoxy group in themixture, one part by weight benzyl triethyl ammonium chloride, and g 0.2parts by weight hydroquinone. Dispersion of the rubber particles isachieved by blending with a Brabender mixer equipped with sigma blades.The mixture is heated to 80 C. until the reaction between acid groupsand glycidyl groups is substantially complete. One weight percentdit-butyl perbenzoate is added and the mixture is compression molded for15 minutes at 100 C. to yield a hard molded article which is insolublein acetone.

EXAMPLE 5 The procedures of Example 4 are repeated with the differencethat the thermoset prepolymer is formed from a monomer mixturecomprising 30 mole percent glycidyl methacrylate, 30 mole percentmethacrylonitrile, and 40 mole percent methyl methacrylate.

EXAMPLE 6 The procedures of Examples 1 5 are repeated with thedifference that the dispersion of prepolymer, methyl methacrylate, andgraded-rubber particles is diluted with methyl methacrylate .until thetotal concentration of unreacted methyl methacrylate is 40 weightpercent. This material is sprayed on wood, metal, and polymericsubstrates and crosslinked thereon by exposing the resultant coating toan electron beam having average energy of about 95,000 electron volts ina nitrogen atmosphere.

EXAMPLE 7 7 An acrylic prepolymer is prepared by slowly adding a mixtureof 86 parts by weight of methacrylic acid, 814 parts by weight of methylmethacrylate, 100 parts by weight of methacrylonitrile and 20 parts byweight of 2,2 azobis (2 methylpropionitrile) to 1,000 parts by weight ofrapidly stirred toluene maintained at reflux temperature under anitrogen atmosphere. Upon completion of the addition, 2.0 parts byweight of 2,2 azobis (2 methylpropionitrile) dissolved in 40 parts byweight of toluene is added over a period of 30 minutes. The mixture ismaintained at 1 10 C. for an additional 2 hours. I

The reaction mixture is cooled to 50 C., and there is added 142 parts byweight of glycidyl methacrylate, .5

parts by weight of 2,6 ditertiary butyl phenol and 5 parts by weight oftrimethylbenzylarnmonium iodide. The mixture is heated at 85 C. forseveral hours until 95 percent of the glycidyl group, as shown byinfrared,

is reacted. The prepolymer is coagulated, mixed with graded-rubberparticles and molded.

EXAMPLE 8 The procedure of Example 7 is repeated except for thedifference of using 43 parts by weight of methacrylic acid and 72 partsby weight of glycidyl methacrylate.

EXAMPLE 9 EXAMPLE 10 The procedure of Example 7 is repeated exceptforthe difference of using 350 parts by weight methacrylic acid and 5 partsby weight of glycidyl methacrylate.

EXAMPLE 11 EXAMPLE 12 The procedure of Example 1 is repeated except forthe difference of using 28 parts by weight of glycidyl methacrylate and18 parts by weight of methacrylic acid.

The terms acrylate and acrylates, when used herein without a modifierdistinguishing between esters of acrylic and methacrylic acid, shall beunderstood to include both. This, of course, does not apply to thenaming of a specific compound.

The foregoing examples are illustrative of the invention defined in theamended claims. Those skilled in the art will be aware thatmodifications may be made therein without departing from the scope ofthe invention as set forth in the appended claims.

We claim:

1. A thermoset product molded from (A) about 60 to about 95 parts byweight of an alpha-beta, olefinicallyunsaturated, copolymer of monovinylmonomers consisting essentially of carbon, hydrogen and oxygen, havingaverage molecular weight between about 1,000 and about 25,000 andcontaining between about 0.5 and about units of alpha-beta olefinicunsaturation per 1,000 units molecular weight, said copolymer ofmonovinyl monomers having a alpha-beta olefinic unsaturation pendantfrom its principal carbon-to-carbon chain through an ester linkage andbeing the polymeric product formed by reacting carboxyl of an alpha-betaolefinically unsaturated monocarboxylic acid with epoxide of an additioncopolymer of monovinyl monomers of which at least one constituentmonomer is an epoxy-functional acrylate or methacrylate, and (B) acrosslinking amount of about 5 to about 40 parts by weight ofgraded-rubber particles having alpha-beta olefinic-unsaturation, surfacefunctionality and crosslinked through the olefinic I unsaturation ofsaid copolymer of monovinyl monomers and the olefinic unsaturation ofsaid graded-rubber particles, said graded-rubber particles consistingessentially of 1. about to about 90 weight percent of a core ofcrosslinked acrylic polymer consisting essentially a. a minor andcrosslinking amount of a dior trifunctional monomer containing 2 or morenonconjugated terminal ethylenic groups, said minor and crosslinkingamount not exceeding about 20 mole percent of the core reactants, and

b. a remainder consisting essentially of a monofunctional monoacrylate,said remainder constituting at a minimum about 80 mole percent of thecore reactants, and

2. about 90 to about 10 weight percent of an outer shell having glasstransition temperature above that of said core and consistingessentially of the polymerization product of monomer mixtures selectedfrom the group consisting of a. about 65 to about 98 mole percent methylmethacrylate and about 2 to about 35 mole percent of an epoxy-functionalacrylate, and

b. about 2 to about 35 mole percent of an epoxyfunctional acrylate andabout 65 to about 98 mole percent of a mixture consisting essentially ofesters of acrylic or methacrylic acid and a C C monohydric alcohol, C Cmonovinyl hydrocarbons, 0 to 30 mole percent of a difunctional compoundselected from the group consisting of divinyl benzene and diesters ofacrylic or methacrylic acid and a C C dihydric alcohol and 0 to 30 molepercent of a monomer selected from acrylonitrile, methacrylonitrile andvinyl acetate,

and being provided with alpha-beta olefinic-unsaturation, surfacefunctionality. by reacting resultant epoxy groups on the surfaces ofsaid outer shell with an alpha-beta olefinically unsaturatedmonocarboxylic acid.

2. A thermoset produce molded from (A) about 70 to about 90 parts byweight of an alpha-beta, olefinically-unsaturated, copolymer ofmonovinyl monomers consisting essentially of carbon, hydrogen andoxygen, having average molecular weight between about 1,000

and about 25,000 and containing between about 0.5 and about 5 units ofalpha-beta olefinic unsaturation per 1,000 units molecular weight, saidcopolymer of monovinyl monomers having alpha-beta olefinic unsaturationpendant from its principal carbon-to-carbon chain through an esterlinkage and being the polymeric product formed by reacting carboxyl ofan alpha-beta olefinically unsaturated monocarboxylic acid with epoxideof an I addition copolymer of monovinyl monomers of which at least oneconstituent monomer is an epoxy-functional acrylate or methacrylate, and(B) a crosslinking amount about 10 to aboutl30 parts by weight ofgraded-rubber particles having alpha-beta olefinic-unsaturation, surfacefunctionality and crosslinked through the olefinic unsaturation of saidcopolymer of monovinyl monomers and the olefinic unsaturation of saidgraded-rubber particles, said graded-rubber particles consistingessentially of 1. about 10 to about 90 weight percent of a core ofcrosslinked acrylic polymer consisting essentially a. a minor andcrosslinking amount of a dior trifunctional monomer selected from thegroup consisting of divinyl benzene, diesters of acrylic or methacrylicacid and a C C dihydric alcohol, and triesters of acrylic or methacrylicacid and a C C trihydric alcohol, said minor and crosslinking amount notexceeding about 20 mole percent of the core reactants and a remainderconsisting essentially of a monofunctional monoacrylate, said remainderconstituting at a minimum about mole percent of the core reactants, and2. about to about 10 weight percent of an outer shell having glasstransition temperature above that of said core and consistingessentially of the polymerization product of monomer mixtures selectedfrom the group consisting of a. about 65 to about 98 mole percent methylmethacrylate and about 2 to about 35 mole percent of an epoxy-functionalacrylate, and

b. about 2 to about 35 mole percent of an epoxyfunctional acrylate andabout 65 to about 98 mole percent of a mixture consisting essentially ofesters of acrylic or methacrylic acid and a C,

C monohydric alcohol, C C monovinyl hydrocarbons, 0 to 30 mole percentof a difunctional compound selected from the group consisting of divinylbenzene and diesters of acrylic or methacrylic acid and a C C dihydricalcohol and 0 to 30 mole percent of a monomer selected fromacrylonitrile, methacrylonitrile and vinyl acetate,

and being provided with alpha-beta olefinic-unsaturation, surfacefunctionality by reacting resultant epoxy groups on the surfaces of saidouter shell with an alpha-beta olefinically unsaturated monocarboxylicacid.

3. A thermoset product in accordance with claim 2 wherein saidalpha-beta olefinically unsaturated monocarboxylic acid is acrylic acid.

4. A thermoset product 'in accordance with claim 2 whereinmonocarboxylic acid is methacrylic acid.

said alpha-beta olefinically unsaturated 5. A thermoset product inaccordance with claim 2 wherein said outer shell has glass transitiontemperature at least 50 C. above that of said core.

6. A thermoset product in accordance with claim 2 wherein said majoramount is about 80 to about 98 mole percent and said minor andcrosslinking amount is about 2 to about 20 mole percent.

7. A thermoset product in accordance with claim 2 wherein said copolymerof vinyl monomers has average molecular weight in the range of 2,000 toabout 1 15,000.

8. A thermoset product in accordance with claim 2 wherein said copolymerof vinylmonomers contains between about 0.7 and about 3.5 units ofalpha-beta olefinic unsaturation per 1 ,000 units molecular weight. 1

9. A thermoset product molded from (A) about 70 to about 90 parts byweight-of an alpha-beta olefinicallyunsaturated'copolymer of monovinylmonomers consisting essentially of carbon, hydrogen and oxygen, havingaverage molecular weight between about 2,000 and about 15,000andcontaining about 0.7 to about 3.5 units of alpha-beta olefinicunsaturation per 1,000 units molecular weight, said copolymer ofmonovinyl monomers having alpha-beta olefinic unsaturation pendant fromits principal carbon-to-carbon chain through an ester linkage and beingthe polymeric product formed by reacting carboxyl of an alpha-betaolefinically unsaturated monocarboxylic acid with epoxide of an additioncopolymer of monovinyl monomers of 3 which at least one constituentmonomer is an epoxyfunctional acrylate or methacrylate, and (B) acrosslinking amount of about 10 to about 30 parts by weight ofgraded-rubber particles having alpha-beta olefinicunsaturation, surfacefunctionality and crosslinked through the olefinic unsaturation of saidcopolymer of monovinyl monomers and the olefinic unsaturation of saidgraded-rubber particles, said graded-rubber particles consistingessentially of i b. a remainder consisting essentially of amonofunctional monoacrylate, said remainder constituting at a minimumabout 80 mole percent of the core reactants, and

2. between 90 and weight percent of an outer shell having glasstransition temperature above that of said core and consistingessentially of the polymerization product of monomer mixtures selectedfrom the group consisting of a. about 65 to about 98 mole percent methylmethacrylate and about 2 to about mole percent of an epoxy-functionalacrylate, and

. about 2 to about 35 mole percent of an epoxyfunctional acrylate andabout 65 to about 98 mole percent of a mixture consisting essentially ofesters of act lic or methacrylic acid and a C C monohy ['10 alcohol, C 9monovinyl hydrocarbons, O to 30 mole percent of a monomer I selectedfrom I acrylonitrile, methacrylonitrile and vinyl acetate, and beingprovided with alpha-beta olefinic-unsaturation, surface functionality byreacting resultant epoxy groups on the surfaces of said outer shell withan alpha-beta olefinically-unsaturated monocarboxylic acid, and beingfurther characterized in that the average weight of the outer shells ofsaid graded-rubber particles is between about 10 and about 60 percent ofthe average weight of the cores of the same. 10. A thermoset product inaccordance with claim 9 wherein said copolymer of vinyl monomers is acopolymer of glycidyl methacrylate and an ester of acrylic ormethacrylic acid and a C C monohydric alcohol which has been reactedwith acrylic or 1. between 10 and 90 weight percent of a core of 40methacrylic acid.

11. A thermoset product in accordance with claim 9 wherein saidcopolymer of vinyl monomers is a copolymer of glycidyl methacrylate, anester of acrylic ormethacrylic acid and a C C monohydric alcohol, andmethacrylonitrile which has been reacted with acrylic or methacrylicacid.

12. A thermoset product in accordance with claim 9 wherein saidcopolymer of vinyl monomers is a copolymer of acrylic or methacrylicacid and methacrylonitrile which has been reacted with glycidylmethacrylate.

13. A thermoset product in accordance with claim 9 wherein saidparticles of graded rubber have average diameter in the range of 0.04to 1. micron.

2. about 90 to about 10 weight percent of an outer shell having glasstransition temperature above that of said core and consistingessentially of the polymerization product of monomer mixtures selectedfrom the group consisting of a. about 65 to about 98 mole percent methylmethacrylate and about 2 to about 35 mole percent of an epoxy-functionalacrylate, and b. about 2 to about 35 mole percent of an epoxy-functionalacrylate and about 65 to about 98 mole percent of a mixture consistingessentially of esters of acrylic or methacrylic acid and a C1 - C8monohydric alcohol, C8 - C9 monovinyl hydrocarbons, 0 to 30 mole percentof a difunctional compound selected from the group consisting of divinylbenzene and diesters of acrylic or methacrylic acid and a C2 - C6dihydric alcohol and 0 to 30 mole percent of a monomer selected fromacrylonitrile, methacrylonitrile and vinyl acetate, and being providedwith alpha-beta olefinic-unsaturation, surface functionality by reactingresultant epoxy groups on the surfaces of said outer shell with analpha-beta olefinically unsaturated monocarboxylic acid.
 2. A thermosetproduce molded from (A) about 70 to about 90 parts by weight of analpha-beta, olefinically-unsaturated, copolymer of monovinyl monomersconsisting essentially of carbon, hydrogen and oxygen, having averagemolecular weight between about 1,000 and about 25,000 and containingbetween about 0.5 and about 5 units of alpha-beta olefinic unsaturationper 1,000 units molecular weight, said copolymer of monovinyl monomershaving alpha-beta olefinic unsaturation pendant from its principalcarbon-to-carbon chain through an ester linkage and being the polymericproduct formed by reacting carboxyl of an alpha-beta olefinicallyunsaturated monocarboxylic acid with epoxide of an addition copolymer ofmonovinyl monomers of which at least one constituent monomer is anepoxy-functional acrylate or methacrylate, and (B) a crosslinking amountabout 10 to about 30 parts by weight of graded-Rubber particles havingalpha-beta olefinic-unsaturation, surface functionality and crosslinkedthrough the olefinic unsaturation of said copolymer of monovinylmonomers and the olefinic unsaturation of said graded-rubber particles,said graded-rubber particles consisting essentially of
 2. about 90 toabout 10 weight percent of an outer shell having glass transitiontemperature above that of said core and consisting essentially of thepolymerization product of monomer mixtures selected from the groupconsisting of a. about 65 to about 98 mole percent methyl methacrylateand about 2 to about 35 mole percent of an epoxy-functional acrylate,and b. about 2 to about 35 mole percent of an epoxy-functional acrylateand about 65 to about 98 mole percent of a mixture consistingessentially of esters of acrylic or methacrylic acid and a C1 - C8monohydric alcohol, C8 - C9 monovinyl hydrocarbons, 0 to 30 mole percentof a difunctional compound selected from the group consisting of divinylbenzene and diesters of acrylic or methacrylic acid and a C2 - C6dihydric alcohol and 0 to 30 mole percent of a monomer selected fromacrylonitrile, methacrylonitrile and vinyl acetate, and being providedwith alpha-beta olefinic-unsaturation, surface functionality by reactingresultant epoxy groups on the surfaces of said outer shell with analpha-beta olefinically unsaturated monocarboxylic acid.
 2. between 90and 10 weight percent of an outer shell having glass transitiontemperature above that of said core and consisting essentially of thepolymerization product of monomer mixtures selected from the groupconsisting of a. about 65 to about 98 mole percent methyl methacrylateand about 2 to about 35 mole percent of an epoxy-functional acrylate,and b. about 2 to about 35 mole percent of an epoxy-functional acrylateand about 65 to about 98 mole percent of a mixture consistingessentially of esters of acrylic or methacrylic acid and a C1 - C8monohydric alcohol, C8 - C9 monovinyl hydrocarbons, 0 to 30 mole percentof a monomer selected from acrylonitrile, methacrylonitrile and vinylacetate, and being provided with alpha-beta olefinic-unsaturation,surface functionality by reacting resultant epoxy groups on the surfacesof said outer shell with an alpha-beta olefinically-unsaturatedmonocarboxylic acid, and being further characterized in that the averageweight of the outer shells of said graded-rubber particles is betweenabout 10 and about 60 percent of the average weight of the cores of thesame.
 3. A thermoset product in accordance with claim 2 wherein saidalpha-beta olefinically unsaturated monocarboxylic acid is acrylic acid.4. A thermoset product in accordance with claim 2 wherein saidalpha-beta olefinically unsaturated monocarboxylic acid is methacrylicacid.
 5. A thermoset product in accordance with claim 2 wherein saidouter shell has glass transition temperature at least 50* C. above thatof said core.
 6. A thermoset product in accordance with claim 2 whereinsaid major amount is about 80 to about 98 mole percent and said minorand crosslinking amount is about 2 to about 20 mole percent.
 7. Athermoset product in accordance with claim 2 wherein said copolymer ofvinyl monomers has average molecular weight in the range of 2,000 toabout 15,000.
 8. A thermoset product in accordance with claim 2 whereinsaid copolymer of vinyl monomers contains between about 0.7 and about3.5 units of alpha-beta olefinic unsaturation per 1,000 units molecularweight.
 9. A thermoset product molded from (A) about 70 to about 90parts by weight of an alpha-beta olefinically-unsaturated copolymer ofmonovinyl monomers consisting essentially of carbon, hydrogen andoxygen, having average molecular weight between about 2,000 and about15,000 and containing about 0.7 to about 3.5 units of alpha-betaolefinic unsaturation per 1,000 units molecular weight, said copolymerof monovinyl monomers having alpha-beta olefinic unsaturation pendantfrom its principal carbon-to-carbon chain through an ester linkage andbeing the polymeric product formed by reacting carboxyl of an alpha-betaolefinically unsaturated monocarboxylic acid with epoxide of an additioncopolymer of monovinyl monomers of which at least one constituentmonomer is an epoxy-functional acrylate or methacrylate, and (B) acrosslinking amount of about 10 to about 30 parts by weight ofgraded-rubber particles having alpha-beta olefinic-unsaturation, surfacefunctionality and crosslinked through the olefinic unsaturation of saidcopolymer of monovinyl monomers and the olefinic unsaturation of saidgraded-rubber particles, said graded-rubber particles consistingessentially of
 10. A thermoset product in accordance with claim 9wherein said copolymer of vinyl monomers is a copolymer of glycidylmethacrylate and an ester of acrylic or methacrylic acid and a C1 - C8monohydric alcohol which has been reacted with acrylic or methacrylicacid.
 11. A thermoset product in accordance with claim 9 wherein saidcopolymer of vinyl monomers is a copolymer of glycidyl methacrylate, anester of acrylic or methacrylic acid and a C1 -C8 monohydric alcohol,and methacrylonitrile which has been reacted with acrylic or methacrylicacid.
 12. A thermoset product in accordance with claim 9 wherein saidcopolymer of vinyl monomers is a copolymer of acrylic or methacrylicacid and methacrylonitrile which has been reacted with glycidylmethacrylate.
 13. A thermoset product in accordance with claim 9 whereinsaid particles of graded rubber have average diameter in the range of0.04 to
 1. micron.